Forget about Mapplegate (could there be a worse name for a ‘controversy’?), Apple continues to sell iPhone 5s just as quickly as Foxconn can produce them. Indeed, if anything, Apple has had trouble meeting pent up demand for its 6th generation iPhone up until recently.

Recently, we reported on how stricter quality control measures requested by Apple as a means to limit the number of scratched iPhone 5s caused a temporary slow down in production. Now in a follow up report from the WSJ, an official with Foxconn added that the iPhone 5 is the most difficult product the company has ever assembled.

“The iPhone 5 is the most difficult device that has ever assembled. To make it light and thin, the design is very complicated,” said an official at the company who declined to be named. “It takes time to learn how to make this new device. Practice makes perfect. Our productivity has been improving day by day.”

That’s Apple all right, pushing the boundaries.

The report also adds that the iPhone 5 employs a special coating material that makes it more prone to getting scuffed up. Also note that the iPhone 5 back casing uses anodized aluminum as opposed to the glass used on the back of the iPhone 4 and 4S. The aluminum does lend itself more easily to scratching but the upside is that it’s much more durable.